Biological Indicators Of Soil Health Research Articles

Early impacts of cover crop selection on soil biological parameters during a transition to organic agriculture

AbstractAlthough Texas is not widely known for organic production, it is responsible for most organic peanut production in the United States. When managed effectively, this can be a lucrative practice due to consumer demands. However, farmers pursuing organic management must undergo a 3‐year transition period to obtain United States Department of Agriculture certification, which is often associated with depressed yields. The objective of this study was to measure the impact of organic management and cover crop selection on biological indicators of soil health during the second year of transitioning to an organic cotton–peanut rotation in West Texas. We conducted a field study at two locations, and soil health indicators including in situ respiration, carbon mineralization, enzyme activities, and phospholipid fatty acids (PLFAs) were measured. The use of a cover crop resulted in generally greater biological activities compared to the fallow after only one cover crop rotation, representing early elevated biological activities under plots treated with a cover crop. However, cover crop species selection typically does not affect soil biological parameters. Cover crop use also did not contribute to yield losses when compared to a fallow treatment. When comparing organic management to conventional management, both sites experienced elevated PLFA counts under organic management. Importantly, results indicated that although reduced peanut yields could be expected under transitional organic management, this was not cover crop species‐specific, nor was it a guarantee. Given the economic risk of organic management for farmers, this study will benefit producers deciding whether to pursue organic production and cover cropping.

Vermifiltration and sustainable agriculture: unveiling the soil health-boosting potential of liquid waste vermicompost

Vermifiltration is a promising technique that can help recover nutrients from wastewater for further use in agriculture. We conducted a field experiment to assess the effectiveness of vermicompost produced from the vermifiltration of liquid waste (manure and food production waste) and how it can affect the soil health and yield of a squash crop. We tested the effect of three rates of vermicompost (low, medium, and high) applied over two consecutive years and measured physical, chemical, and biological soil health indicators, squash yield, and nutritional status. The results showed that the use of vermicompost, especially at a high rate, increased total soil carbon, total nitrogen, potentially mineralizable nitrogen, and particulate organic matter, as well as the activity of C-N-P cycling enzymes, as compared to a control with only inorganic fertilization. The yield of the squash crop remained stable, while the crop nutritional value improved as the levels of boron and copper in the treated squash increased. These findings indicate an improvement in soil health after the use of vermicompost. Overall, results strongly support using this type of vermicompost as a sustainable management approach to recycle nutrients and enhance soil health.

Crop, livestock, and forestry integration to reconcile soil health, food production, and climate change mitigation in the Brazilian Cerrado: A review

Integrated crop–livestock (ICL) and crop–livestock–forestry (ICLF) systems have been widely adopted in the Brazilian Cerrado. In this study, we gathered the publications regarding the effects of the ICL and ICLF systems on soil health, plant and animal production, and carbon (C) balance and then synthesized them in comparable terms, aiming to evaluate the sustainability of these systems in a broader and comprehensive approach. On the basis of the evidence from 65 peer-reviewed publications, it was observed that adopting integrated systems can improve soil health in the Brazilian Cerrado. With a few exceptions, positive effects on chemical, physical, and biological indicators of soil health were observed in most of the studies that comprised our data. Accordingly, the results showed that the ICL and ICLF systems can improve plant yield and animal production, but special attention regarding the grazing regime and tree management (e.g., spacing, pruning, and thinning) is required. Moreover, soil C accumulation fully offsets soil N2O emissions, underscoring the feasibility of using the ICL and ICLF systems for decreasing the C footprint of agricultural commodities in this region. The research assembled in this review has undoubtedly advanced our knowledge regarding integrated systems in the Brazilian Cerrado. However, there are still significant knowledge gaps that should be addressed, such as their effects on soil physics and biology. Despite these shortcomings, our literature review demonstrates that the ICL and ICLF systems are essential strategies to intensify agricultural production in the Brazilian Cerrado while ensuring sustainability.

Soil quality reflects microbial resource availability and drives rhizosphere microbiome variation in Ghanaian cocoa farms

Cocoa (Theobroma cacao L.) is an important crop in Ghana and the source of livelihood for hundreds of thousands of smallholder farmers. Maintaining soil quality on these farms is critical to ensuring the long-term viability of cocoa farming and preventing deforestation to meet rising demand. However, increasing attention to soil health has revealed a significant knowledge gap related to the soil microbiome in cocoa production systems. Using a nested design of sixteen smallholder cocoa farms in agroforestry or monoculture, on different soil quality classes and in different agroecological zones, a study was conducted to identify 1) drivers of rhizosphere microbial diversity and community composition across scales and 2) the extent of microbial differentiation between soil quality classes. Soil quality had far greater impacts than agroecological zone or agroforestry vs. monoculture management on microbial diversity and community composition, accounting for 17 % of variation in prokaryotes and 10 % in fungi. Good-quality and poor-quality soils contrasted in soil and root parameters, creating variable microbial resources, which led to differences in microbial community composition and the relative abundance of specific taxa. Soil organic matter and root traits were key drivers of community composition in good-quality soils, while permanganate-oxidizable carbon was relatively more important in poor-quality soils. These results underscore the importance of considering rhizosphere microbial communities in assessments of soil quality and highlight taxa that may serve as biological indicators of soil health in cocoa agroforestry systems.

Biological soil health indicators are sensitive to shade tree management in a young cacao (Theobroma cacao L.) production system

Cacao agroforestry systems can offer important benefits, such as greenhouse gas mitigation, microclimate regulation and improved soil health. The selection of tree species for cacao agroforestry systems is a critical step impacting cacao yields, as well as the environmental and economic sustainability of the production system. However, the effects of different tree species on soil processes and functions have been poorly studied. We assessed a series of soil health indicators in a five-year-old agroforestry trial located in the Ecuadorian Amazon. The following treatments: “control” (cacao monoculture), “timber” (cacao with Cedrelinga cateniformis Ducke; a leguminous tree), “fruit” (cacao with Bactris gasipaes), “N-fix” (cacao with Erythrina velutina Wild) and “mixed” (cacao with C. cateniformis + E. velutina) were replicated 3 times in randomized blocks. The experiment was managed organically with low levels of external inputs. We collected soil, litter and leaf samples of cacao trees at two different distances (∼2 m and ∼ 6 m) from the shade tree. Biological (potential soil respiration, and macrofauna abundance, richness and Shannon diversity), chemical (pH, CEC, total C and N, macro and micronutrients and Cd), and physical (bulk density and water holding capacity) soil health indicators were measured. Additionally, we analysed nutrients and Cd in cacao leaves and litter. Results showed positive effects of the “timber” and “mixed” treatments on biological soil health indicators, primarily earthworm abundance and potential respiration, as compared to cacao monocultures. Treatment effects on potential respiration showed different trends in litter versus soil, indicating that effects of shade trees on litter respiration do not transfer directly to soil respiration. Physical and chemical soil indicators, including available Cd which is irrelevant in the context of food safety regulations, did not show any differences among the treatments. Five years after establishment, no significant differences in yields were found among the control and any of the shade tree treatments.

Cover crop-mediated soil carbon storage and soil health in semi-arid irrigated cropping systems

Cover cropping is considered a climate-smart strategy to regenerate low-fertility soils in arid and semi-arid regions. However, the mechanisms of soil organic carbon (SOC) storage and soil health improvement in semi-arid irrigated cropping systems are poorly understood. The main goal of this study was to evaluate cover crop effects on various physical, chemical, and biological indicators of soil health in an irrigated silage corn (Zea mays L.)–sorghum [Sorghum bicolor (L.) Moench] rotation and understanding how changes in soil health contribute to SOC storage. We evaluated various SOC and nitrogen (N) pools, and microbial community structure under cover crop mixture of grasses, brassicas, and legumes (GBL), grasses and brassicas (GB), grasses and legumes (GL), and no cover crops (NCC) control for four years. Grasses included annual ryegrass (Lolium multiflorum Lam.) and winter triticale (× Triticosecale Wittmack), brassicas included turnip (Brassica rapa subsp. rapa L.) and daikon radish (Raphanus sativus var. Longipinnatus Bailey), and legumes included pea (Pisum sativum subsp. arvense L.) and berseem clover (Trifolium alexandrinum L.). Soil C pools: SOC, potentially mineralizable C, microbial biomass C, mineral-associated organic C (MAOC), and particulate organic C (POC) were greater with cover crops than without, but the effects were not consistent in all study years. Soil organic N was also greater under cover crops than under NCC. Soil C-to-N (C:N) ratio increased over the years but was similar among treatments. Cover crops used N and soil water to grow, significantly reducing soil inorganic N content and water-filled pore spaces in the first two years. However, fungal and bacterial communities grew better under cover crops with a high fungi-to-bacteria ratio than under NCC. The soil MAOC content was related to microbial community and enzyme activity while POC was affected by soil physicochemical conditions, specifically soil pH and mineral N availability, highlighting two major pathways of SOC sequestration in semi-arid cropping systems. This study showed how cover crops enhance SOC storage and soil health in semi-arid cropping systems.

Diversified vegetation types on rangelands promote multiple soil‐based ecosystem services

AbstractRangelands have the potential to be provisioners of ecosystem services, including livestock products, carbon storage and greenhouse gas regulation, water and nutrient cycling, wildlife habitat, and biodiversity. Due to their vast extent and landscape heterogeneity, the degree to which different ecological components of rangelands contribute to ecosystem services can be varied. Soils are the foundation of rangeland health and associated ecosystem services. While many studies have examined the effect of grazing intensity on rangeland ecosystem services, few studies have looked at the broader rangeland landscape and how managing varying vegetation types can influence soil‐based ecosystem services. In this study, a suite of physical, chemical, and biological soil health indicators were measured in various vegetation types found within a working cattle ranch, including coastal live oak woodlands, coastal scrublands, annual grassland, and restored native perennial grassland. Based on the measured soil health indicators, results from this study show scrubland significantly diverges from other vegetation types, having higher water infiltration and plant available water, carbon stocks, and a more diverse microbial community that drives more dynamic cycling of carbon and nitrogen. Strategically maintaining scrubland on unproductive, highly erosive slopes downgradient of highly productive grassland areas could maintain forage production while protecting water quality and increasing carbon storage. These results highlight the relevance of holistically evaluating rangeland operations to assess soil function and ecosystem services and the potential risks and co‐benefits of varying vegetation types. Ultimately, process‐based linkages described here may provide a working example of how to manage ranches as functional mosaics of strategically maintained vegetation types.

Tracking Soil Health Changes in a Management-Intensive Grazing Agroecosystem

Management-intensive Grazing (MiG) has been proposed to sustainably intensify agroecosystems through careful management of livestock rotations on pastureland. However, there is little research on the soil health impacts of transitioning from irrigated cropland to irrigated MiG pasture with continuous livestock rotation. We analyzed ten soil health indicators using the Soil Management Assessment Framework (SMAF) to identify changes in nutrient status and soil physical, biological, and chemical health five to six years after converting irrigated cropland to irrigated pastureland under MiG. Significant improvements in biological soil health indicators and significant degradation in bulk density, a physical soil health indicator, were observed. Removal of tillage and increased organic matter inputs may have led to increases in β-glucosidase, microbial biomass carbon, and potentially mineralizable nitrogen, all of which are biological indicators of soil health. Conversely, trampling by grazing cattle has led to increased bulk density and, thus, a reduction in soil physical health. Nutrient status was relatively stable, with combined manure and fertilizer inputs leading to stabilized plant-available phosphorous (P) and increased potassium (K) soil concentrations. Although mixed effects on soil health were present, overall soil health did increase, and the MiG system appeared to have greater overall soil health as compared to results generated four to five years earlier. When utilizing MiG in irrigated pastures, balancing the deleterious effects of soil compaction with grazing needs to be considered to maintain long-term soil health.

Getting the basics right on soil enzyme activities: A comment on Sainju et al. (2022)

AbstractSoil enzyme activities have been measured since the mid‐20th century to help understand how agricultural management practices impact nutrient cycling, and are now considered biological indicators of soil health. However, misconceptions persist about what soil enzyme activities represent and how activities can or cannot be interpreted. The publication by Sainju et al. in Agrosystems, Geosciences & Environment that seeks to evaluate how soil enzyme activities relate to crop yields exemplifies many of these issues. We therefore provide a constructive diagnosis and critique of five common misunderstandings and even errors exemplified by this work. Our ultimate goal in this critique is to catalyze a better understanding of soil enzyme activities and identify where research is needed to close knowledge gaps.

Empirical approach for developing production environment soil health benchmarks

Defining quantitative soil health benchmarks can support efforts to improve soil quality and meet broader ecosystem services goals, while simultaneously helping field-level benchmarking of soil health on farms. However, soil health metrics in agricultural systems require edaphic context, notably climate, soil texture and classification, as well as cropping system information for optimal interpretation. Soil samples (n = 1328) from New York State (USA) with Land Resource Regions (LRR), texture, and cropping system information were analyzed for eight physical and biological soil health indicators (i.e., soil organic matter, permanganate-oxidizable carbon, respiration, protein, available water capacity, wet aggregate stability from 0 to 15 cm depth, and penetration resistance from 0 to 15 and 15–45 cm), from which population distribution functions were determined. Production environment soil health (PESH) benchmarks were derived as potential management goals for four soil texture groups and six cropping systems by proposing the 75th and 90th percentile for each factorial class. Finer-textured (sand content <50%) soils and Pasture and Mixed Vegetable cropping systems generally had the highest values for soil health benchmarks, followed by Dairy Crop and Orchard systems, then Annual Grain, and lastly Processing Vegetable systems. Soil organic matter PESH benchmarks for silt loam soils, defined by the 75th percentile, ranged from 4.2% (Annual Grain and Processing Vegetable) to 5.9% (Pasture). Long Island (LRR-S) had soil organic matter PESH benchmarks that were, on average, 0.7% numerically lower than the rest of New York State (LRRs-L&R). This implies that regional PESH benchmarks within a state or region may be warranted if edaphic context is considerably different.

Sampling for biological indicators of soil health: How does sampling methodology affect research results?

A wide variety of soil sampling methods have been adopted, yet limited research has addressed how sampling methods can impact research results particularly for spatially variable soil properties. To address these concerns, we intensively sampled two existing soil health trials in Texas for analysis of soil extracellular enzymatic activities (EEAs), permanganate oxidizable C (POXC), soil organic C (SOC), and pH. The data generated was used to quantify the effect of composite sampling, sampling position (in-row vs between-row), and number of samples on statistical results. We compared a Monte Carlo simulation approach with a traditional power analysis to quantify the impact of the number of samples on our results. Calculated composite sampling resulted in lower statistically significant results compared to discrete sampling, demonstrating lower sensitivity of composite sampling. Sampling in-row resulted in greater values specifically for EEAs, pH, POXC, and SOC. Simulation generated estimated number of samples were mainly driven by the effect size and spatial variation. EEAs were highly variable, resulting in a higher estimated number of samples as compared to other soil properties such as POXC and SOC. In our study with two sites, soil with greater clay content resulted in overall lower estimated number of samples compared to a relatively sandy soil, demonstrating a greater sampling requirement for sandy soil. The simulation approach had a weak correlation with traditional power analysis. The simulation predicted lower estimated number of samples when compared to power analysis, which can help save cost in the long run. Overall, factors like composite sampling, sampling in-row vs between-row, and number of samples taken did impact research results. The impact of these sampling strategies on soil parameters of interest needs to be investigated to achieve the most accurate research results in soil science.

Long term influence of alternative corn cropping practices and corn-hay rotations on soil health, yields and forage quality

Modifications to continuous corn production systems can reduce environmental impacts and soil degradation, yet the social viability of these modifications is linked to the degree to which they also influence yields and crop quality. In this study, we focus on forage production systems and evaluate how yields, crop quality, soil health indicators, and associated ecosystem services are influenced by corn-hay rotation treatments, cover cropping, and tillage reduction in silage production using a unique 10-year dataset from Borderview Research Farm in Vermont, United States. Physical, chemical, and biological soil health indicators were monitored annually alongside yields and crop quality in a randomized complete block design experiment. We use a mixed model analysis of variance approach to demonstrate significant influences of time and treatments on yields, crop quality and soil health parameters (at p &amp;lt; 0.05). The winter rye cover crop treatment had no significant influence in this study. No-till significantly increased aggregate stability and had no significant effect on other metrics. When cover crop and no-till were combined, they significantly increased soil organic matter content, respiration and aggregate stability. The cover crop, no-till, and no-till cover crop combination treatments had no significant effect on yields or forage quality, suggesting these conservation practices can be adopted without sacrificing yields. Our study also found that corn-hay rotations can significantly increase soil organic matter, respiration, aggregate stability, and crude protein content compared to continuous corn, but they can negatively influence active carbon, total dry matter yield and digestibility. The length of rotation influences the degree to which corn-hay rotations maintain or reduce yields when compared to continuous corn. Shorter rotations of perennial forages (4 years of hay, 6 years of corn) can sustain dry matter yields that are not significantly different from continuous corn, but longer perennial forage rotations (8 years of hay, 2 years of corn) will significantly reduce overall dry matter yields. Among the treatments, no-till in combination with cover cropping in corn silage fields, and a rotation of 4 years of hay to 6 years of corn are likely to achieve the greatest overall benefits in forage production systems.

Cropping systems with perennial vegetation and livestock integration promote soil health

AbstractSoil health can differ across cropping systems because of variation in edaphic and management factors. We evaluated how biological indicators of soil health (soil organic matter [SOM], permanganate oxidizable carbon [POXC], mineralizable carbon [MinC], autoclaved‐citrate‐extractable [ACE] protein, and potentially mineralizable nitrogen [PMN]) compared across four common Wisconsin cropping systems: grazed cool‐season pastures, forage‐based rotations that included perennial legumes or grasses, annual rotations receiving manure, and annual rotations receiving synthetic fertilizers. Biological indicators of soil health were up to 195% greater in pastures than other cropping systems. MinC, POXC and PMN were 10%–90% greater in forage‐based rotations than annual cropping systems, but only MinC and POXC were greater in annual systems with manure compared to those without manure by 35% and 7%, respectively. Perennial vegetation and livestock integration offer the greatest potential to increase biological indicators of soil health in agricultural lands.

Concentration‐dependent response of soil parameters and functions to trifluoroacetic acid

AbstractDespite growing environmental concerns about perfluoroalkyl and polyfluoroalkyl substances (PFAS) worldwide, the ultra‐short‐chain PFAS, for example, trifluoroacetic acid (TFA), have been largely neglected in the context of soil pollution. Given the persistence and increasing occurrence of TFA in the soil environment, accumulated TFA could impact soil properties and functions. Therefore, we investigated the effects of a wide range of concentrations of TFA (0.001–100 μg g−1) on chemical, physical and biological indicators of soil health, using a six‐week microcosm experiment. Our results showed that TFA treatments decreased soil pH, sulphate content, soil respiration, litter decomposition and bacterial abundance, and increased phosphate content (p &lt; 0.05). These effects were observed for TFA concentrations ≥1 μg g−1. As expected, because of its strong acidity, TFA decreased soil pH, and this change likely contributed to effects on other soil parameters and functions, for example, reducing bacterial abundance and soluble nutrients. However, importantly, TFA clearly also affected soil parameters at concentrations at which soil pH was not changed. Soil aggregation, fungal abundance, and enzyme activities were not affected by TFA in this study. Considering the current reported environmental levels of TFA of &lt;2.4 μg g−1, only litter decomposition would be affected under current field conditions. Our data also show that future accumulation of higher concentrations, or hotspots of TFA, will likely negatively affect soils with similar properties as our test soil. Thus, we demonstrated that microbial processes can be impacted by the accumulation of the ‘forever chemical’ TFA in the tested sandy, low organic matter soil.Highlights Trifluoroacetic acid (TFA) decreased soil pH, respiration, litter decomposition and bacterial abundance. TFA affected soil soluble nutrients. TFA affected litter decomposition at 1 μg g−1 with no change in soil pH. Effects of TFA on soil enzyme activity and aggregation and fungal abundance were negligible.

Sampling for Biological Indicators of Soil Health: How Does Sampling Methodology Effect Research Results?

Sampling for Biological Indicators of Soil Health: How Does Sampling Methodology Effect Research Results?

Nematode communities indicate anthropogenic alterations to soil dynamics across diverse grasslands

Nematode communities are meaningful biological indicators of soil health and soil processes across different grassland types and management practices and analyses of nematode communities provide insight into structure, function, and sensitivity or resilience across multiple ecosystems. In three model grasslands: meadow steppe (MS), typical steppe (TS), and alpine meadow (AM), this current research examined responses of soil nematode communities and related edaphic characteristics to grazing, mowing, and crop cultivation at two soil depths. The research fills a critical knowledge gap by resolving multidirectional influences between local conditions, grassland management practices, and nematode communities. Across grassland types, nematode abundance in AM was greater than MS and TS grasslands, and nematodes were more abundant near the soil surface. Cultivation resulted in greater nematode abundance compared to all other management practices, and generally, bacterivores were the most dominant nematode trophic group. The TS and MS grasslands had relatively more bacterivores, exhibiting substantial influences on soil mineralization and organic matter decomposition pathways. The AM grassland showed relatively more plant feeding nematodes, driving soil mineralization pathways. Among the three management practices, crop cultivation had the greatest impact on nematode community structure and the soil environment, especially in relatively sensitive AM grasslands. In fact, AM soil environments responded most dramatically to cultivation, with nematode abundance, soil quality, and food web complexity increasing. However, soil ecosystem stability, food web reliance, and food web response to resources decreased in cultivated AM soils. Results indicate that unique environmental characteristics in the Qinghai-Tibet plateau drive substantially different AM grassland nematode community structure and soil conditions compared to TS or MS grasslands. As anthropogenic pressures on these ecosystems mount, it is critical to understand how different management practices influence grassland nematode communities, with cascading effects through soil environments.

Quantification of the global impact of agricultural practices on soil nematodes: A meta-analysis

Agricultural practices significantly affect soil biodiversity and functions, altering biogeochemical cycles and potentially compromising food production. Increased employment of sustainable agricultural practices is of growing policy concern and requires a better understanding and quantification of how agriculture affects soil functioning. We conducted a worldwide meta-analysis by computing 4855 effect sizes from 103 publications to quantify the effect of agricultural practices on soil nematodes, known to be key biological indicators of soil health. Our meta-analysis summarized the effects of tillage, pesticides use, fertilization, manipulation of above-ground plant including cover crop, rotation and agricultural system shift (the conversion from the conventional to conservation or organic agriculture systems). We quantified how each agricultural practice alters nematode indices of ecological relevance including the absolute abundance of trophic groups, the taxonomic richness and diversity and the food web structure based on functional guilds. At the global level, organo-mineral fertilization, conservation system, cover crop and nematicides exhibited the greatest effect sizes (averaged all nematode indices) while herbicides, plant association, mineral fertilization and tillage had the lowest ones. At the level of trophic groups, the agricultural practices had varying impacts, e.g. crop rotation mainly reduced the abundance of the plant-feeding nematodes (−47%), cover crop mainly increased the abundance of omnivore-predators (+80%) while organic fertilization predominately promoted bacterial (+113%) and fungal feeders (+141%). Crop rotation reduced the absolute abundance of plant feeders by 47% when the rotation is longer than 2 years. At the community level, chemical inputs, monoculture and pesticide application reduced nematode abundance, the food web structure and favoured copiotrophic nematode communities. Biocides and nematicides reduced total abundance, Shannon diversity and the food web complexity of soil nematode (structure index). Using meta-regressions, our meta-analysis revealed that the effect of agricultural practices depends on the time since the last agricultural intervention (e.g. input of fertilizers, pesticide application) and on how long a practice has been adopted. This study will be a useful aid for decision maker to better manage soil nematode community and to identify gaps in current available literature. In providing the direction and magnitude of soil nematode responses to agricultural practices, the effect size produced by this study are critical in facilitating worldwide modelling of soil biodiversity under global change scenarios.

Interrelationships of Chemical, Physical and Biological Soil Health Indicators in Beef-Pastures of Southern Piedmont, Georgia

The study of interrelationships among soil health indicators is important for (i) achieving better understanding of nutrient cycling, (ii) making soil health assessment cost-effective by eliminating redundant indicators, and (iii) improving nitrogen (N) fertilizer recommendation models. The objectives of this study were to (i) decipher complex interrelationships of selected chemical, physical, and biological soil health indicators in pastures with history of inorganic or broiler litter fertilization, and (ii) establish associations among inorganic N, potentially mineralizable N (PMN), and soil microbial biomass (SMBC), and other soil health indicators. In situ soil respiration was measured and soil samples were collected from six beef farms in 2017 and 2018 to measure selected soil health indicators. We were able to establish associations between easy-to-measure active carbon (POXC) vs. PMN (R2 = 0.52), and N (R2 = 0.43). POXC had a noteworthy quadratic relationship with N and nitrate, where we found dramatic increase of N and nitrate beyond an inflection point of 500 mg kg−1 POXC. This point may serve as threshold for soil health assessment. The relationships of loss-on-ignition (LOI) carbon with other soil health indicators were discernable between inorganic- and broiler litter-fertilized pastures. We were able to establish association of SMBC with other soil variables (R2 = 0.76) and there was detectable difference in SMBC between inorganic-fertilized and broiler litter-fertilized pastures. These results could be useful for cost-effective soil health assessment and optimization of N fertilizer recommendation models to improve N use efficiency and grazing system sustainability.

Biological characterization and regulation of soil health.

How to determine the soil health status effectively is the basic issue to realize the agriculture green development. In the existing soil health assessment system, the importance of soil organi-sms in the maintenance of soil health is rarely considered. From the perspective of soil biological health, we discussed the connotation of soil health, and summarized the biological indicators of soil health, including soil microorganisms, soil enzyme activity, soil micro-food web and earthworm. Based on the above-mentioned indicators, the regulation approaches were elaborated from the aspects of crop and soil management practices. In addition, the future research on soil biological health was prospected. The main aim of this study is to enhance the understanding of scientists and decision makers on the maintenance of soil biological health, and to give full consideration of the important role of soil organisms in ecosystem services.

On Quantifying Water Quality Benefits of Healthy Soils

AbstractDespite decades of research demonstrating links between many agricultural practices and water quality, the ability to predict water quality on the basis of changes in soil health remains severely limited. By better understanding how soil health affects downstream water quality, researchers and policymakers could prioritize different conservation practices while exploring more innovative soil health management strategies. Focusing on the Great Lakes region, we describe the value and challenges of different approaches to linking soil health and water quality, specifically applying nitrogen and phosphorus mass balances and adapting simulation models to better incorporate changing soil health conditions. We identify critical research needs, including paying greater attention to a broad suite of conservation practices and to biological indicators of soil health. We also discuss key barriers to farmer adoption of conservation practices from field to national scales, highlighting that improved scientific understanding alone is insufficient to drive widespread change.